#include"my_stdio.h"

mFILE* mfopen(const char* filename, const char* mode)
{
    int fd = -1;
    if (strcmp(mode, "r") == 0)
    {
        fd = open(filename, O_RDONLY);
    }
    else if (strcmp(mode, "w") == 0)
    {
        fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0666);
    }
    else if (strcmp(mode, "a") == 0)
    {
        fd = open(filename, O_CREAT | O_WRONLY | O_APPEND, 0666);
    }

    if (fd < 0) return NULL;

    mFILE* mf = (mFILE*)malloc(sizeof(mFILE));
    if (!mf) 
    {
        close(fd);
        return NULL;
    }

    mf->fileno = fd;
    mf->flag =  FLUSH_LINE; //默认行刷新
    mf->cap = SIZE;
    mf->size = 0;

    return mf;
}

void mfflush(mFILE* stream)
{
    if (stream->size > 0)
    {
        write(stream->fileno, stream->outbuffer, stream->size);
        stream->size = 0;
    }
}

int mfwrite(const void* ptr, int num, mFILE* stream)
{
    // 1.拷贝
    memcpy(stream->outbuffer + stream->size, ptr, num);
    stream->size += num;
    
    // 2.检测是否要刷新
    if (stream->flag == FLUSH_LINE && stream->size > 0  && stream->outbuffer[stream->size - 1] == '\n')
    {
        //当遇到\n 缓冲区中有数据 刷新方式是行刷新时刷新
        mfflush(stream);
    }
    return num;
}

void mfclose(mFILE* stream)
{
    if (stream->size > 0)
    {
        //刷新
        mfflush(stream);
    }
    close(stream->fileno);
}


